Cardiovascular and renal function an their controlling systems have changed during phylogenetic development of the vertebrates in order to adapt to a variety of environments. We intended to define a functional evolution of the kidney, which initially emerged as a primitive excretory device and culminated in the highly specialized mammalian kidney. During the current year, we studied: 1) Renal function in birds. Bird kidneys possess dual circulation; renal arterial and renal portal systems. We have studied the anatomy of renal vasculatures in the fowl, and established surgical and analytical techniques for measurement of blood pressure, renal function and renin activity. 2) Role of renin-angiotensin and adrenergic nervous system in control of blood pressure (BP). Many bird species demonstrate atherosclerosis and elevated BP. Acute and chronic treatments of conscious fowl with propranolol decreased BP and heart rate and increased plasma catecholaminess, suggesting that beta adrenergic function is important for maintaining BP. On the other hand, aglomerular toadfish decreased BP markedly by an injection of angiotensin converting enzyme inhibitor. 3) Vasopressor and depressor action of angiotensin in fowl. (Val5) ANG II (native) caused primarily a pressor response in the anesthetized chicken whereas a depressor followed by a pressor action was noted in conscious chicken. This depressor effect was not blocked by propranolol, atropine, methysergide or vasopressin inhibitors, but was completely abolished by angiotensin antagonists, suggesting that it may possibly be a direct effect on blood vessels. We will continue to determine cardiovascular and renal function in primitive animals by using both in vivo and in vitro preparations. Comparative studies provide unique experimental models which are not obtainable in mammals and provide better understanding into mammalian physiology.